Aspartic acid lactoglobulin

Titration curve of /3-lactoglobulin. At very low values of pH (<2) all ionizable groups are protonated. At a pH of about 7.2 (indicated by horizontal bar) 51 groups (mostly the glutamic and aspartic amino acids and some of the histidines) have lost their protons. At pH 12 most of the remaining ionizable groups (mostly lysine and arginine amino acids and some histidines) have lost their protons as well. 

Schilling, K. and Waldmann-Meyer, H., The interaction of bromophenol blue with serum albumin and gamma-globuhn in acid medium. Arch. Biochem. Biophys. 64, 291-301, 1956 Cohen, A.H., Temperature jump studies of the binding of bromophenol blue to beta-lactoglobulin in the vicinity of the N-R transition, J. Biol. Chem. 245,738-745,1970 Harruff, R.C. and Jenkins, W.T., The binding of bromophenol blue to aspartate aminotransferase. Arch. Biochem. Biophys. 

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